1. Field of the Invention
This invention pertains to the field of weather-resistant epoxy coatings.
2. Description of the Related Art
Cycloaliphatic epoxy resins prepared by hydrogenation of glycidyl ethers of Bisphenol A or other di- or polyphenols may be reacted with selected curatives to form coatings that are resistant to UV degradation. Cycloaliphatic epoxy resins are prepared by the process described in U.S. Pat. No. 3,336,241. These resins are much less reactive with conventional epoxy curatives than are the phenolic-based glycidyl ethers. In a paper, Bauer, R. S., Proceedings Ninth Water-Borne and Higher Solids Coatings Symposium, Feb. 1982, New Orleans, pg 208, a method is described for curing these cycloaliphatic epoxy resins with specially prepared saturated polyamides. These curatives require an induction or pre-reaction period of about one hour prior to application of the coating system. Failure to pre-react the resin with the polyamide curative led to rapid loss of gloss and surface defects of the coating such as blushing and blemishing.
It has been learned that this induction period may be eliminated through use of JEFFAMINE.RTM. polyoxyalkylene amines. The tendency for these products to blush on curing is lowered (Waddill, H. G., and Sellstrom, K. B., Decorative Epoxy Coatings Cured with Polyetheramines, Epoxy Resin Formulators Meeting, May 1982, Boston, MA). However, curing of the cycloaliphatic epoxy resins with polyoxyalkylene amines is quite sluggish and requires a prohibitively lengthy curing period.
My invention is a method for curing these cycloaliphatic epoxy resins which are superior to the prior art described above.